The CBIC Certified Infection Control Exam Study Guide (6th edition) emphasizes that when a potential cluster of infections is identified, the first priority is situational awareness. Before implementing control measures or advanced laboratory analysis, the infection preventionist must determine whether the cases are epidemiologically linked. Identifying the location of the patients—such as whether they are on the same unit, service, or clinic—is the essential first step in assessing the likelihood of transmission or a common source.

Option C is correct because determining patient location allows the IP to evaluate spatial and temporal relationships, which form the foundation of outbreak investigation. If the patients are colocated, this may indicate shared staff, equipment, or environmental exposure, guiding immediate and targeted interventions.

Cohorting patients (Option A) is premature without confirming proximity or transmission risk. Monitoring hand hygiene (Option B) is an important control measure but should follow confirmation of potential spread or shared risk factors. Pulsed-field gel electrophoresis (Option D) is an advanced molecular typing method and is never an initial step; it is reserved for later stages when epidemiologic evidence suggests related cases.

For the CIC® exam, this question tests understanding of outbreak investigation sequencing. The Study Guide consistently reinforces that defining who, where, and when comes before interventions or laboratory typing, making determination of patient location the correct first action.